If it doesn’t what does it do?
the screen turns on
It vibrates
Depends how literal you want to be.
In the loose sense of, “Someone is trying to make a phone call to me and my device has registered that fact and is now alerting me in some way, whether through sound, light or movement” yes I’d still just say it’s “ringing”.
I refer to a phone notifying you of a call - with a ring or otherwise - as “going off.” However, after looking this up, that apparently means “to explode” (possibly metaphorically, depending on which source you trust).
So far, even on vibrate or silent, my phone has not done that.
I also say “your phone is going off” as it can refer to either the alarm, incoming call, or other notifications. It’s definitely an accepted alternative meaning for the phrase.
“Going off” can also mean “be in the process of spoiling / going bad” when referring to foodstuffs, which I only mention to point out that the phrase has at least one alternative use beyond exploding, even if alarms and such aren’t considered. More usually in the past tense of “gone off”, but it gets some use in the present tense.
Yeah. Put your phone in a vacuum.
It’s still making sound, you just can’t hear it over the roar of the air pump